ALPR often functions as the core module of “intelligent” transportation infrastructure applications. License plate recognition can be employed to identify a vehicle by automatically reading a license plate utilizing image processing and character recognition technology. A license plate recognition operation can be performed by locating the license plate in an image, segmenting the characters in the plate, and performing an OCR (Optical Character Recognition) operation with respect to the characters identified.
License plate localization can be employed to accurately and efficiently locate a license plate from an image of the vehicle. Most prior art approaches for locating a license plate involve the detection of a region whose features match the license plate. Such features may include shape (e.g., rectangle), texture containing strong edges from the text and the plate boundary, and color (if the color of the plate is known). Since there are problems such as poor image quality due to ambient lighting conditions, image perspective distortion, interference characters, etc., such prior art approaches are unable to accurately locate the license plate.
Based on the foregoing, it is believed that a need exists for an improved license plate localization method and system based on a combination of a top-down texture analysis and a bottom-up connected component analysis, as will be described in greater detail herein.